As rewritable photo-recording media, there have been proposed photo-recording media utilizing change in absorption spectrum before and after photoreaction of photochromic compounds. In the proposed photo-recording media, however, when recorded information is read out, the readout thereof must be carried out by means of light falling within the wavelength region at which the photochromic compounds absorb light. Accordingly, it follows that the light used in reading out such records is light for reading out the recorded information and, at the same time, is also light for erasing said recorded information. On that account, there was such a serious practical problem that to carry out reproduction of the information is essentially to destroy said information, and hence when the information recorded in the photochromic compounds is read out, said information is destroyed and no information can be read out again.
Japanese Patent L-O-P Publin. No. 209186/1987 in this connection discloses photomemory materials which are said to be those capable of inhibiting disappearance of memories recorded in photochromic compounds, said photomemory materials being prepared by dissolving or dispersing in solid substances having a cholesteric liquid crystal phase such photochromic compounds as capable of changing their molecular structure by irradiation with light different in wavelength. In this process, however, there is involved such a problem that a procedure for synthesizing the cholesteric liquid crystal which is a medium in which the dye is dissolved or dispersed is much complicated, because said cholesteric liquid crystal must have in the molecule asymmetric carbon atoms and also must be optically resolved.